Using #bit

[Haplo]

<font face="Courier New" size=-1>Hi there
There are two ways of changing a pin's state. For example:

output_high(PIN_B0);

and:
#bit PORTB0=0x06.0
PORTB0=1;

The second method produces a much smaller code, but does it run a risk of the correct data memory bank not being selected?

__Ali</font>
___________________________
This message was ported from CCS's old forum
Original Post ID: 144514472

[david smith]

:= There are two ways of changing a pin's state. For example:
:=
:=output_high(PIN_B0);
:=and:
:=#bit PORTB0=0x06.0
:=PORTB0=1;

I always use the latter just for readability alone.
I know of no drawbacks. Provides clean syntax for 1-bit variables to ports.
For clarification to other readers, here's a usage snippet:
#BYTE PORTB = 6
...
#BIT spHighSW = PORTB.2
#BIT spMedSW = PORTB.1
#BIT spLowSW = PORTB.0
...
IF (spLowSW == 0) { ... do something
___________________________
This message was ported from CCS's old forum
Original Post ID: 144514474

[Tomi]

The difference:
the first form with STANDARD_IO (default) setting not only sets the pin to high but sets the port pin to output.
The second form just sets the bit in the port_x register. If that port pin is in input state (the associated bit is 1 in the tris_x register) then the port pin never changes.
___________________________
This message was ported from CCS's old forum
Original Post ID: 144514477

[Woody]

The advantage of using the biult in functions is portability of code.
For instance the PIC18F252 can be pin compatible with PIC16F876 and provides a good migration path if the code won't fit. Writing in a style which allows compilation for either part greatly eases the pain of migration if the code won't fit.

Readability can be enhanced by using #defines to rename the actual pins and IO directives to control how the compiler deals with the TRIS registers.

#if defined(__PCM__)
#include <16f876.h>
#elif defined(__PCH__)
#include <18f252.h>
#endif

#define SELECT_PIN PIN_B0

#pragma USE STANDARD_IO(B)
/* Wth this directive, port bit and TRIS bit are changed */
output_low (SELECT_PIN );

#pragma USE FAST_IO(B);
/* Now only port pit is changed */
output_low (SELECT_PIN );
___________________________
This message was ported from CCS's old forum
Original Post ID: 144514487